Such a technology has been known, by which the surface of a substrate is improved by providing an organic-inorganic composite film having an inorganic oxide and an organic group on the surface of glass and other matrices.
By coating a solution, in which silicon alkoxide, substituted silicon alkoxide having a part of alkoxyl group substituted by fluoroalkyl group, alcohol, water and acid (or a base) are blended, on the surface of a glass substrate and burning the same, glass having an organic-inorganic composite film having water repellency coated thereon has been disclosed in Japanese Unexamined Patent Application No. H4-338137.
An organic-inorganic composite film coated article having water repellency, which is treated by a composition in which a mixture of perfluoroalkylalkylsilane and completely hydrolyzable silane (for example, tetrachlorosilane) is dissolved in a solvent, preferably a non-water based solvent, has been known in Japanese Unexamined Patent Application No. H8-239653.
An organic-inorganic composite film coated article having water repellency, which is treated by a composition in which a compound containing a chlorosilyl group and a silane compound containing a fluoroalkyl group are dissolved in an alcohol-based solvent has been disclosed in Japanese Unexamined Patent Application No. H11-71682.
An organic-inorganic composite film in these technologies is produced by a so-called sol-gel method in which a solvent including a hydrolyzable silane compound and a silane compound having water repellent group are coated on a substrate and dried thereon. In the sol-gel method, since the solvent evaporation is progressed in line with formation of an oxide bonding, remarkably fine pores exist in a film when the temperature is 400° C. or less, and hardness of the film is not high. In order to remove the pores and to increase the hardness of the film, burning thereof at a temperature of 500 through 600° C. is indispensable. However, an organic group such as a water repellent group contributing to improvement of the surface is decomposed at such a temperature. Therefore, in the above-described technologies, drying and hardening of the film are carried out at 250° C. or less. The organic-inorganic composite film thus obtained does not become a film having high hardness as in oxides and ceramics that are obtained by, for example, a melting method although the obtained organic-inorganic composite film has oxides as the main compounds.
For example, where such an article coated with an organic-inorganic composition film is used outdoors, the article is exposed to such situations where sand is blown thereonto, and the film surface is easily impaired, resulting in a loss of the improved characteristics. Also, by wiping off the surface thereof to remove adhered dust, soil and sand, the film may be impaired and peeled off. Further, even in a case where no dust is adhered, minor damage occurs on the surface due to friction between a cloth made of hard fabric, a brush, etc., (for example, wiping off the window glass of a vehicle by a wiper, etc.,), wherein this damage fosters deterioration in the characteristics.
The present invention was developed in view of the above-described and other problems, and it is therefore an article of the invention to provide an article coated with an organic-inorganic composite film having high hardness which withstands outdoor uses, water repellency and/or other functional properties, and a coating liquid composition for producing this coated article, and a method for producing the coated article with excellent productivity.